From e72d79d6bcee564dbdf83169c743bbd3f8438108 Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Fri, 2 Nov 2018 09:39:50 +0800 Subject: [PATCH] btrfs: Refactor find_free_extent loops update into find_free_extent_update_loop We have a complex loop design for find_free_extent(), that has different behavior for each loop, some even includes new chunk allocation. Instead of putting such a long code into find_free_extent() and makes it harder to read, just extract them into find_free_extent_update_loop(). With all the cleanups, the main find_free_extent() should be pretty barebone: find_free_extent() |- Iterate through all block groups | |- Get a valid block group | |- Try to do clustered allocation in that block group | |- Try to do unclustered allocation in that block group | |- Check if the result is valid | | |- If valid, then exit | |- Jump to next block group | |- Push harder to find free extents |- If not found, re-iterate all block groups Signed-off-by: Qu Wenruo Reviewed-by: Su Yue [ copy callchain from changelog to function comment ] Signed-off-by: David Sterba --- fs/btrfs/extent-tree.c | 231 +++++++++++++++++++++++------------------ 1 file changed, 131 insertions(+), 100 deletions(-) diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 215937f51cc5..d242a1174e50 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -7277,7 +7277,9 @@ struct find_free_extent_ctl { /* RAID index, converted from flags */ int index; - /* Current loop number */ + /* + * Current loop number, check find_free_extent_update_loop() for details + */ int loop; /* @@ -7479,6 +7481,117 @@ static int find_free_extent_unclustered(struct btrfs_block_group_cache *bg, return 0; } +/* + * Return >0 means caller needs to re-search for free extent + * Return 0 means we have the needed free extent. + * Return <0 means we failed to locate any free extent. + */ +static int find_free_extent_update_loop(struct btrfs_fs_info *fs_info, + struct btrfs_free_cluster *last_ptr, + struct btrfs_key *ins, + struct find_free_extent_ctl *ffe_ctl, + int full_search, bool use_cluster) +{ + struct btrfs_root *root = fs_info->extent_root; + int ret; + + if ((ffe_ctl->loop == LOOP_CACHING_NOWAIT) && + ffe_ctl->have_caching_bg && !ffe_ctl->orig_have_caching_bg) + ffe_ctl->orig_have_caching_bg = true; + + if (!ins->objectid && ffe_ctl->loop >= LOOP_CACHING_WAIT && + ffe_ctl->have_caching_bg) + return 1; + + if (!ins->objectid && ++(ffe_ctl->index) < BTRFS_NR_RAID_TYPES) + return 1; + + if (ins->objectid) { + if (!use_cluster && last_ptr) { + spin_lock(&last_ptr->lock); + last_ptr->window_start = ins->objectid; + spin_unlock(&last_ptr->lock); + } + return 0; + } + + /* + * LOOP_CACHING_NOWAIT, search partially cached block groups, kicking + * caching kthreads as we move along + * LOOP_CACHING_WAIT, search everything, and wait if our bg is caching + * LOOP_ALLOC_CHUNK, force a chunk allocation and try again + * LOOP_NO_EMPTY_SIZE, set empty_size and empty_cluster to 0 and try + * again + */ + if (ffe_ctl->loop < LOOP_NO_EMPTY_SIZE) { + ffe_ctl->index = 0; + if (ffe_ctl->loop == LOOP_CACHING_NOWAIT) { + /* + * We want to skip the LOOP_CACHING_WAIT step if we + * don't have any uncached bgs and we've already done a + * full search through. + */ + if (ffe_ctl->orig_have_caching_bg || !full_search) + ffe_ctl->loop = LOOP_CACHING_WAIT; + else + ffe_ctl->loop = LOOP_ALLOC_CHUNK; + } else { + ffe_ctl->loop++; + } + + if (ffe_ctl->loop == LOOP_ALLOC_CHUNK) { + struct btrfs_trans_handle *trans; + int exist = 0; + + trans = current->journal_info; + if (trans) + exist = 1; + else + trans = btrfs_join_transaction(root); + + if (IS_ERR(trans)) { + ret = PTR_ERR(trans); + return ret; + } + + ret = do_chunk_alloc(trans, ffe_ctl->flags, + CHUNK_ALLOC_FORCE); + + /* + * If we can't allocate a new chunk we've already looped + * through at least once, move on to the NO_EMPTY_SIZE + * case. + */ + if (ret == -ENOSPC) + ffe_ctl->loop = LOOP_NO_EMPTY_SIZE; + + /* Do not bail out on ENOSPC since we can do more. */ + if (ret < 0 && ret != -ENOSPC) + btrfs_abort_transaction(trans, ret); + else + ret = 0; + if (!exist) + btrfs_end_transaction(trans); + if (ret) + return ret; + } + + if (ffe_ctl->loop == LOOP_NO_EMPTY_SIZE) { + /* + * Don't loop again if we already have no empty_size and + * no empty_cluster. + */ + if (ffe_ctl->empty_size == 0 && + ffe_ctl->empty_cluster == 0) + return -ENOSPC; + ffe_ctl->empty_size = 0; + ffe_ctl->empty_cluster = 0; + } + return 1; + } + return -ENOSPC; +} + /* * walks the btree of allocated extents and find a hole of a given size. * The key ins is changed to record the hole: @@ -7489,6 +7602,20 @@ static int find_free_extent_unclustered(struct btrfs_block_group_cache *bg, * * If there is no suitable free space, we will record the max size of * the free space extent currently. + * + * The overall logic and call chain: + * + * find_free_extent() + * |- Iterate through all block groups + * | |- Get a valid block group + * | |- Try to do clustered allocation in that block group + * | |- Try to do unclustered allocation in that block group + * | |- Check if the result is valid + * | | |- If valid, then exit + * | |- Jump to next block group + * | + * |- Push harder to find free extents + * |- If not found, re-iterate all block groups */ static noinline int find_free_extent(struct btrfs_fs_info *fs_info, u64 ram_bytes, u64 num_bytes, u64 empty_size, @@ -7496,7 +7623,6 @@ static noinline int find_free_extent(struct btrfs_fs_info *fs_info, u64 flags, int delalloc) { int ret = 0; - struct btrfs_root *root = fs_info->extent_root; struct btrfs_free_cluster *last_ptr = NULL; struct btrfs_block_group_cache *block_group = NULL; struct find_free_extent_ctl ffe_ctl = {0}; @@ -7731,106 +7857,11 @@ loop: } up_read(&space_info->groups_sem); - if ((ffe_ctl.loop == LOOP_CACHING_NOWAIT) && ffe_ctl.have_caching_bg - && !ffe_ctl.orig_have_caching_bg) - ffe_ctl.orig_have_caching_bg = true; - - if (!ins->objectid && ffe_ctl.loop >= LOOP_CACHING_WAIT && - ffe_ctl.have_caching_bg) - goto search; - - if (!ins->objectid && ++ffe_ctl.index < BTRFS_NR_RAID_TYPES) + ret = find_free_extent_update_loop(fs_info, last_ptr, ins, &ffe_ctl, + full_search, use_cluster); + if (ret > 0) goto search; - /* - * LOOP_CACHING_NOWAIT, search partially cached block groups, kicking - * caching kthreads as we move along - * LOOP_CACHING_WAIT, search everything, and wait if our bg is caching - * LOOP_ALLOC_CHUNK, force a chunk allocation and try again - * LOOP_NO_EMPTY_SIZE, set empty_size and empty_cluster to 0 and try - * again - */ - if (!ins->objectid && ffe_ctl.loop < LOOP_NO_EMPTY_SIZE) { - ffe_ctl.index = 0; - if (ffe_ctl.loop == LOOP_CACHING_NOWAIT) { - /* - * We want to skip the LOOP_CACHING_WAIT step if we - * don't have any uncached bgs and we've already done a - * full search through. - */ - if (ffe_ctl.orig_have_caching_bg || !full_search) - ffe_ctl.loop = LOOP_CACHING_WAIT; - else - ffe_ctl.loop = LOOP_ALLOC_CHUNK; - } else { - ffe_ctl.loop++; - } - - if (ffe_ctl.loop == LOOP_ALLOC_CHUNK) { - struct btrfs_trans_handle *trans; - int exist = 0; - - trans = current->journal_info; - if (trans) - exist = 1; - else - trans = btrfs_join_transaction(root); - - if (IS_ERR(trans)) { - ret = PTR_ERR(trans); - goto out; - } - - ret = do_chunk_alloc(trans, flags, CHUNK_ALLOC_FORCE); - - /* - * If we can't allocate a new chunk we've already looped - * through at least once, move on to the NO_EMPTY_SIZE - * case. - */ - if (ret == -ENOSPC) - ffe_ctl.loop = LOOP_NO_EMPTY_SIZE; - - /* - * Do not bail out on ENOSPC since we - * can do more things. - */ - if (ret < 0 && ret != -ENOSPC) - btrfs_abort_transaction(trans, ret); - else - ret = 0; - if (!exist) - btrfs_end_transaction(trans); - if (ret) - goto out; - } - - if (ffe_ctl.loop == LOOP_NO_EMPTY_SIZE) { - /* - * Don't loop again if we already have no empty_size and - * no empty_cluster. - */ - if (empty_size == 0 && - ffe_ctl.empty_cluster == 0) { - ret = -ENOSPC; - goto out; - } - empty_size = 0; - ffe_ctl.empty_cluster = 0; - } - - goto search; - } else if (!ins->objectid) { - ret = -ENOSPC; - } else if (ins->objectid) { - if (!use_cluster && last_ptr) { - spin_lock(&last_ptr->lock); - last_ptr->window_start = ins->objectid; - spin_unlock(&last_ptr->lock); - } - ret = 0; - } -out: if (ret == -ENOSPC) { /* * Use ffe_ctl->total_free_space as fallback if we can't find -- 2.30.2